1. Field
Various features relate to gutters integrally connected to through mold vias in Molded Laser Package (MLP) Packages for pressure relief for preventing solder shorts.
2. Background
Solder shorts are becoming more common when using a surface mount technology (SMT) process on molded laser package (MLP) packages. Tightened top ball pitch and thinner packages used in the manufacturing process contribute to the increase in solder shorts. Furthermore, through mold via limitations in manufacturing and the presence of moisture in packages leads to solder shorts due to insufficient through mold via volume and the creation of high pressure in the through mold vias. That is, the moisture gets entrapped in the through mold vias resulting in a solder short.
FIG. 1 illustrates a cross sectional view of a pair of solder balls 102 disposed on a pair of electrical contact pads 104 within a substrate 106. A molding layer 108 is located on top of the substrate 106 and a pair of through mold vias 110 extends through the molding layer 108 to the pair of electrical contact pads 104 within the substrate 106. As shown in FIG. 1, the molding layer 108 does not have any relief paths, such as openings, gutters, channels, etc., to relieve the pressure that builds up during the manufacturing process. The buildup of pressure from insufficient through mold via volume causes one or more of the solder balls 102 to expand and flow over a wall 109 in the molding layer, which separates the solder balls 102, causing a short.
FIG. 2 illustrates an example of a solder short 202. A first solder ball 204 comes into contact with a second solder ball 206 resulting in the short 202. As shown, the short is formed when the second solder ball 206, located in a through mold via 208, melts and comes into contact with the first solder ball 204. As described above, the short may be a result of insufficient through mold via volume creating high pressure in the through mold vias and trapping moisture.
Therefore, there is a need for improved Molded Laser Package (MLP) Packages which include a relief path for pressure and reduces the risk of shorting adjacent solder balls.